High Lockout
E2 on Worcester Bosch Greenstar Ri

Your boiler has lost track of the temperature of the water flowing through it because an internal sensor is broken.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Flow sensor defective.

What causes this fault?

This fault occurs when the internal sensor responsible for monitoring the heat of the water leaving the boiler fails or sends an impossible reading to the control board. The most common reason is the sensor's electrical resistance drifting out of range due to age, though it can also be triggered by a loose connection or damaged wiring. Because the boiler no longer knows how hot the water is, it shuts down as a safety precaution to prevent overheating.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E9View →C6View →

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